It is hard to tell if a big rain event will be just heavy rain or truly be a “flooding” event. If it does become a flood, it all happens very quickly. In either case, as a preventative, you can add an algaecide to the pool beforehand and increase the normal levels of chlorination. You might also lower the water level by 1-2 inches but making sure there is still water flowing easily into the skimmer.
Monitor the level of your pool water as the storm continues. If overflowing is imminent, you can let water out of the pool using the following methods:
Pools with D.E. & Sand Filters – The Waste Option
Turn off the pump
Rotate the multi-port valve clockwise to the Waste position
Turn the pump on until the water returns to the proper level
Turn the pump off and rotate the multi-port valve clockwise back to the Filter option
Turn the pump back on
The Waste option will redirect the water flow directly out the backwash line. Remember to rotate the multi-port valve back to the Filter position, otherwise your pool will continue to drain!
Pools with Cartridge Filters – The Hose Bib
Attach a water hose to the Hose Bib and turn to open. The Hose Bib (outdoor faucet) is located on the plumbing as the water is existing the pump. Leave open until the water returns to its proper level. Remember to shut off the hose bib, otherwise your pool will continue to drain!
If your complete backyard is about to flood significantly and water is expected to come in contact with the equipment. You will need to cut power to ALL swimming pool equipment by turning off the circuit breakers to the equipment. Those will be located in the breaker box either attached to the outside of your house or an internal box mounted in a wall of the house or garage.
After the flood
Return the pool water level to it proper operating level
Remove large debris from the pool with a skimmer net
Turn the pump on either through the circuit breakers or timing mechanism
Test the pool water, balance pH, and shock the pool heavily